Simple algorithm for computing the stiffness matrix of composite cross-section

Abstract

The paper proposes an algorithm for computing the stiffness matrix of composite cross-sections made of two or more different materials. Irrespective of the cross-section geometry, the calculation puts forward a numerical solution applying the finite element method (FEM). The cross-section is discretised into fibers and integration over the section area is performed numerically. The required geometric characteristics and stiffness matrix of the entire cross-section are formed by the assembling procedure. Beam theory equations are used for calculating stresses and strains at characteristic points of the cross-section. Materially nonlinear behaviour of concrete and steel is considered. The advantage of the proposed numerical algorithm is that results of satisfying accuracy are obtained in only a few iterations. The algorithm is implemented in own computer program with a straightforward input data procedure.